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Unit One: Matter and Energy for Life Historical Development Cell Theory Biology is “the study of life”. Living things are composed of individual units called cells. Cell - the basic unit of structure and function - smallest unit capable of displaying characteristics of life - the human body is made up of trillions of cells and every one carries out the same life processes as a single-celled organism. Cell biologists - early cell biologists paved the way for cell study - they each built on previous knowledge, modified techniques and changed the way science viewed the origins of life - i.e. a paradigm shift occurred - a paradigm shift is a rare but significant change in how we view the world - often controversial when first proposed but becomes accepted as a major advance in scientific knowledge/understanding. - have discovered the cell theory Cell Theory Four hypotheses include: $ All living things are composed of one or more cells. $ Cells are the basic units of structure and function in all organisms. $ All cells are derived from pre-existing cells. $ In a multicellular organism, the activity of the entire organism depends on the total activity of its independent cells. The idea that life arises from life is called biogenesis. Prior to the cell theory, (late 19th century), many people believed that small living organisms could arise suddenly from non-living or onceliving things. This idea was known as spontaneous generation, later renamed abiogenesis by Thomas Huxley. Scientist contributions: Read: Chapter 1, p 7-10 and handout. (Significant Events in Biological history, related to the Cell Theory) Biology 2201 Contributions of Scientists ( Read p. 7 - 10 ) Aristotle (Ancient Greece) - classified all organisms into 2 kingdoms - plants or animals - wrote that living organisms can arise from non-living matter (abiogenesis) Robert Hooke ( 1635 -1703 ) - did illustrations of once living matter (called them cells) - modification of microscope for clearer images Antony van Leeuwenhoek ( 1632 - 1723 ) - designed simple microscopes ( single lens ) - observed tiny life ( “animalcules” ) in standing water - observed plaque ( bacteria ) Francesco Redi ( 1629 - 1697 ) - conducts a controlled experiment ( ie. maggots in meat ) - refer to Fig. 1.2, p. 8 John Needham ( 1713 - 1781 ) - designs an experiment to support spontaneous generation ( ie. meat broth ) - refer to fig. 1.3, p. 9 Lazzaro Spallanzani ( 1729 - 1799 ) - was skeptical of Needham’s results and conclusions - repeated Needham’s experiment and came to a different conclusion Robert Brown ( 1773 - 1858 ) -observed that cells have a darker region (nucleus) near the centre Matthias Jacob Schleiden ( 1804 - 1881 ) - “ All plants are made of cells” Theodor Schwann ( 1810 -1882 ) - “All animals are made of cells” Alexander C. H. Braun ( 1805 - 1872) - wrote “The cell is the basic unit of life” Rudolph Virchow ( 1821 -1902 ) - “ Where a cell exists, there must have been a pre-existing cell.” Louis Pasteur ( 1822 - 1895 ) - disproves spontaneous generation - concludes that living organisms do not arise from non-living matter - refer to Fig. 1.4, p. 10 for experimental design The Microscope: (Pg 12-22) The microscope permitted scientists to discover the existence of cells in that: - it was a tool with such a great resolving power (the ability to distinguish between small objects close together) that it allowed people to view things that had been too small to see, - lenses had distorted images (color aberrations and blurry images); improvements in glass making and lens grinding removed the distortion effects. Microscopes (Two types:) 1. Light - light energy is passed through the specimen to allow the image to be viewed - glass lenses are used to magnify the image - resolution is commonly -> 1000x - two kinds of light microscopes are: (a) simple -> one lens eg. magnifying glass (b) compound -> two or more lenses (commonly used in labs) 2. Electron - a flow of electrons are used (instead of light) - magnetic lenses are used to focus the electrons - resolution is commonly -> 50 000x (new model can magnify image 500 000x showing molecular structure!) Two types of electron microscopes are: (a) scanning electron microscopes, (SEM) - They scan the surface of a specimen showing details of the outside. (b) transmission electron microscope, (TEM) - They take slices of the specimen to show the inner structures. Light microscopes are adequate for most microscope work and they are less expensive. However, electron microscopes are sometimes chosen over the light microscope as objects can be distinguished more clearly (better resolution), and magnification is so much greater. Videos showing “How to Use” a microscope: Microscope part 1/3 http://www.youtube.com/watch?v=oUsJfttUZw&feature=related&safety_mode=true&persist_safety_mode=1&safe=active Microscope part 2/3 http://www.youtube.com/watch?v=AEzzTCRRlEE&NR=1&safety_mode=true&persist_safety_mode=1&safe =active Microscope part 3/3 http://www.youtube.com/watch?v=btjyDha4II0&feature=related&safety_mode=true&persist_safety_mode=1 &safe=active Slide show showing how to calculate Field of View (FOV): Magnification and field of view Q:\Lane\Microscope Calculations Slideshow.mht Quiz student on “parts of the Microscope!!” Using the Microscope Pre-lab Exercise Using the following diagrams and the information from p.16 in your text, give the function of each of the following parts of the microscope. eyepiece/ocular lens body tube arm stage stage clips course adjustment fine adjustment diaphragm condenser lens revolving nosepiece objective lenses light source/lamp base Cells: Cells may be classified as either: Prokaryotes Eukaryotes eg. bacteria, *archaea eg. plants, animals, fungi, protists smaller in size larger in size less complex structures more complex structures no nucleus - has a concentrated area called a nucleoid has a nucleus and contains membrane-bound *organelles * archaea - live in extreme environments (extreme heat eg.in volcanoes, acid, salt, eg. in Dead Sea or salt flats) * organelles - highly specialized structures that have certain functions (jobs) to do. - work together as a team to carry out cell processes and the work tasks of the cell. eg. making proteins, packaging, transport, etc. **Cell Organelles and Their Functions. - Referring to pages 25-30 in your text, complete the table of the cell organelles. Plant vs. Animal Cell Characteristics Most of the organelles found in animal cells are also found in plant cells ( eg. mitochondria, ribosomes, nucleus, etc.), but there are some differences. Animal Cells Only 1. centrioles 2. lysosomes Plant Cells Only 1. Cell wall - in addition to the cell membrane, a thick outer cell wall gives strength and support to cells. eg. it allows a blade of grass to stand tall. 2. Plastids - double membrane sacs that may be: (a) chloroplasts - contain green coloring pigment, chlorophyl, that traps solar energy in photosynthesis to make food. (b) chromoplasts - contains various pigments also useful tophotosynthesis (responsible for vibrant colors of flower petals) (c) leucoplasts - has no color and functions to store starch Note: Animal cells have small vacuoles and a variety of shapes. Plant cells have large vacuoles and shapes tend to be geometrical eg. rectangular (onion skin - later in the lab!) Animal Cell: Plant Cell: Biology 2201 Animal and Plant Cells Label the following diagrams. This is a/an ______________ cell. 1. __________________ 2. __________________ 3. __________________ 4. __________________ 5. __________________ 6. __________________ 7. __________________ 8. __________________ 9. __________________ 10. __________________ 11. __________________ 12. __________________ 13. __________________ 14. __________________ This is a/an ________________ cell. 1. __________________ 2. __________________ 3. __________________ 4. __________________ 5. __________________ 6. __________________ 7. __________________ 8. __________________ 9. __________________ 10. __________________ 11. __________________ 12. __________________ 13. __________________ Interactive Websites to Teach Cell Organells and Functions: 1) Interactive cell structure game: http://www.wiley.com/legacy/college/boyer/0470003790/animations/cell_structure/cell_s tructure.htm 2) Drag the name of the cell to the part in the diagram (Excellent for recognizing parts of cell in diagram) http://www.mrphome.net/mrp/CellPartsDragandDropres/frame.htm 3) Eucariotic Cell Organelle Identification (pretty neat) http://www.wisc-online.com/Objects/ViewObject.aspx?ID=ap11604 4) Drag and Drop cell organelles (Names) to match their function (good activity) http://www.execulink.com/~ekimmel/drag_gr11/organell.htm 5) Inside a Cell: http://learn.genetics.utah.edu/content/begin/cells/insideacell/ Sites for Biology 2201 Microscope Preparation: Lab #2 How to prepare a wet mount Slide: http://vimeo.com/28981480 Preparing wet mount slides and staining: http://vimeo.com/11687298 Rules for Drawing Biological Sketches (pg. 17 & 18) 1. Give a title. 2. Use 1/4 - 1/3 of the page to draw two or three cells. 3. Indicator lines are to be drawn to the right of the sketch. 4. All indicator lines end parallel to each other and in the same vertical plane. 5. Label in capital letters and PRINT! 6. Use pencil. 7. No shading! For texture or depth, stipple only ( use pencil to make dots). 8. Give magnification (at bottom of sketch). eg. Mag. 400x 9. Give estimated size (when required), ie. Length x width 10. Label fully. Biology 2201 Lab #2 - Animal and Plant Cell Lab Here are the web sites for the lab. The first part is done in the lab (making wet mount) then the drawing of human blood, frog blood, cheek cells, etc... can be put up on the smartboard and done as a class. Animal Cells: Red Blood Cell: http://www.mc.vanderbilt.edu/histology/labmanual2002/labsection2/Blood_hematopoiesis03_files/imag e002.jpg Frog Blood Cell: http://phs.psdr3.org/science/forensics/images/blood/frogblood.jpg Human Cheek Cell: http://schoolworkhelper.net/wp-content/uploads/2011/02/cheekcell.jpg Note: Only draw 3 or 4 cells for the human blood cell, frog blood and the cheek in the field of view. Don’t forget to label them. Plant Cell: Onion Cell for #8 - Proper Biological Drawing http://faculty.ntcc.edu/mhearron/onionep1.jpg Lettuce Cells: http://www.bing.com/images/search?q=lettuce+cells+under+microscope&view=detail&id=3E0C74406 16EA237FBC0745B5B2AF796724C5547&FORM=IDFRIR&adlt=strict Note: For your proper biological drawing of the onion, you are only drawing one onion cell lengthwise on a blank sheet of paper. Follow the guidelines you were given on your handout. Animations describing Passive and Active Transport Great descriptive animation on; Passive and Active Transport: http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.ht ml http://www.northland.cc.mn.us/biology/Biology1111/animations/index_page_ for_animations.htm Lysosome Animation: http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__lysosomes .html Osmosis Animation: http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_osmo sis_works.html Facilitated Difussion Animation: http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_facil itated_diffusion_works.html Difusion Animation: http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_diff usion_works.html Transport Mechanisms - are ways in which materials enter or leave the cell. - crucial in transport is the... Structure of the Cell Membrane The cell membrane functions: (1) not only to protect and (2) contain the cell parts (3) but also to regulate what materials go in and out. Its structure allows it to do this. - it is a double membrane (2 layers) of phospholipid molecules (refer to diagram page 51-2) phosphate heads: - polar and is attracted to water (hydrophilic) - this end able to dissolve in water lipid tails: - nonpolar fatty acids not attracted to water (hydrophobic) - they are insoluble in water This arrangement of polar heads facing outside and nonpolar lipid tails facing inside is what allows the cell membrane to act as a barrier between the tissue fluid (extracellular fluid) and the cytoplasm (intracellular fluid) of the cell. Thus, water, oxygen and carbon dioxide can pass through the cell membrane freely. Other substances, like big glucose molecules or ions must pass through specialized transport proteins. Transport mechanisms may be: A. passive (3 types) 1. Diffusion 2. Osmosis 3. Facilitated Diffusion B. active C. bulk (creation of vesicles) (2 types) 1. Endocytosis 2. Exocytosos A. Passive Transport (3 types) 1. Diffusion - atoms/molecules of substance move randomly, collide and bounce off in all directions eg. perfume diffuses throughout a room -materials diffuse from an area where there is a lot (greater concentration) to an area where there is less (lower conc.) - requires no additional energy (other than kinetic molecular energy) and so is termed passive. - in a closed system, materials will diffuse until they are scattered evenly throughout. - if the substance is colored, the color fades as diffusion continues. - diffusing materials may be solid, liquid or gaseous. Diffusion explains how some molecules move back and forth across the cell membrane, but once molecules have diffused inside, their rate of diffusion slows down. Surface Area to Volume Ratio: (refer to handout) - Having a large surface area relative to its volume increases the area available for materials to diffuse in and out of a cell. - The smaller the surface area/volume ratio, the bigger the cell and the less efficient it will be to diffuse enough materials in to serve the mass of the cell. - Thus when the cell reaches a size where diffusion becomes inefficient, it divides. - Now two small cells have formed, thus increasing the surface/volume ratio and diffusion efficiency. 2. Osmosis Some membranes only allow certain materials to pass through. The membrane is said to be selectively or semi-permeable. When a liquid, usually water, is passing through a selectively permeable membrane, the process is called osmosis. -requires no energy so it is passive -operates from high -> low concentration (ie. ‘along’ the concentration gradient) - osmosis continues until the concentration is the same on both sides of the membrane (ie. equilibrium is reached) Starch, water, and iodine activity Diffusion is occurring with: a) water molecules - water diffuses into the bag in an attempt to equalize the concentration on both sides (obtain equilibrium). Bag swells. b) iodine molecules- iodine diffuses into the bag, reacting with starch, observable as a color change from red-brown to blueblack, but... Some molecules, eg. starch, are too big to diffuse through the bag. The water outside remains the red/brown color of iodine indicating a negative test. (Starch turns blue/black in the presence of iodine.) Osmosis continues even after equilibrium is reached. Molecules are then diffusing in at the same rate as they are diffusing out. We say that osmosis is dynamic. Your cells are being bathed in tissue fluid. Materials the cells need, glucose, oxygen, etc., diffuse from the blood vessel capillaries into the tissue fluid, then across the cell membrane into the cells. Waste products in the cells diffuse out of the cells, into the tissue fluid and into the blood vessels. Question: How will the direction of water flow be affected if the solute concentration outside the cell is: a. higher than inside the cell? b. lower than inside the cell? c. the same as inside the cell? The terms hypertonic, hypotonic, and isotonic refer to the solute concentration of a solution. Hypertonic When cells are placed in a hypertonic solution, we say the solution is hypertonic to the cytoplasm (and the cytoplasm is hypotonic to the solution). Greater solute = lower water concn outside; therefore the greater water concentration is inside . Osmosis will result in more water diffusing out of the cell, where the water concn is less, and continues until equilibrium is reached. Cells shrink. Hypotonic The solution is hypotonic to the cell cytoplasm when the solute concn is lower in the solution than the cytoplasm. Lower solute= higher water concn, so more water will diffuse from the outside to the inside, until equilibrium is reached. Cells swell and may burst before that happens. (Note that the cell cytoplasm was also hypertonic to the outside solution.) Isotonic The solute concentration is the same on both sides of the cell membrane. Osmosis continues with water diffusing into the cell at the same rate as it is diffusing out. No observable change in cell size. The cell cannot prevent this movement of water because it is permeable to water molecules. Refer to page 55 in text to compare all three osmotic conditions in animal and plant cells, paying particular attention to the role played by the cell wall in plant cells. ( use shoe box / balloon for demo.) Students do web link page 57. 3. Facilitated Diffusion Substances that cannot diffuse through the phospholipid layer of the membrane (eg. Molecules that are too big, insoluble in the lipid layer or charged ions) may be transported with the help of specialized transport proteins (refer to p.52). Each transport protein will help only one type of molecule, depending on its shape, size and electrical charge. Two types of transport proteins include: a) carrier proteins - accepts only non-charged particles; eg. glucose - allows the particles to move in or out of cell (see diagram p.57) - changes shape (rocking motion) to transport molecule b) channel proteins - accepts charged particles that are opposite in charge to itself; ie. a negative channel protein accepts a positively charged particle (note Bio Fact p. 58 in text) - has tunnel shape that allows the particle to pass through Reminder: Since no energy is required and materials move along the concn gradient, diffusion, osmosis and facilitated diffusion are all forms of passive transport. B. Active Transport A cell may need to concentrate nutrients for growth inside, completely rid itself of toxic wastes to the outside or create an electrical potentiel across a membrane to allow nerves and muscles to work (see square bullets p.59 for more examples). Passive transport would not be sufficient for this. In active transport... - materials move against the concn gradient (low -> high) - energy is required ( in the form of ATP) - transport proteins are used to make active transport pumps,(like fac. diff. but against the concn gradient.) eg. the sodium-potassium pump allows sodium ions to leave and potassium ions to enter a cell by changing the shape of a transport protein, with the help of an ATP energy molecule. See diagram p.60 for details. C. Bulk Transport (vesicles) Macromolecules may be too big or too polar to be transported by passive or active transport. The cell membrane folds in on itself to create a membrane-enclosed, bubble-like sac,or vesicle. The cell may use these vesicles to take materials in (endocytosis) and expel them out (exocytosis). See p.62-4. Endocytosis has three forms: 1. pinocytosis (“cell-drinking”) - a vesicle is created involving the intake of a small droplet of tissue fluid, together with any dissolved substances or very small particles it may contain. - occurs in nearly all cell types all the time (See p. 62) 2. phagoctosis (cell-eating) - a vesicle is created involving the intake of a large droplet of tissue fluid and matter such as bacteria or bits of organic matter; digestive enzymes are necessary to digest the matter - occurs only in specialized cells; eg. amoeba or macrophages of our immune system 3. receptor-assisted endocytosis - vesicles are created when special molecules with ‘tags’ bond to matching ‘receptors’ on the cell membrane; once inside the vesicle splits in two parts - one carrying receptors returns, once again, to become part of the cell membrane and the other, containing the food molecule, empties into the cell cytoplasm -membrane receptors fit the shape of only one specific molecule; eg. cholesterol (See diagram page 63) Exocytosis - a vesicle is formed using membrane from an organelle; eg. ER, golgi apparatus - the vesicle moves to the cell surface, joins the cell membrane, emptying (secreting) its contents into the tissue fluid; eg. the pancreas secreting the hormone insulin